Transmission mechanism for motor vehicles



m 12,143. w. M. BLAGDEN EI'AL 2,308,351

TRANSMISSION MECHANISM FOR MOTOR VEHICLES s Sheets-Sheet 1 Filed'May 9, 1941 w. M. BLAGDEN rm. 08,351

Jan. 12, 19431 TRANSMISSION MECHANISM FQR MOTOR VEHICLES 5 Sheets-Sheet 2 Filed may 9, 1941 INVENTORS HERBERT PERKINS RTIN BLAGDEN M ATTORNEYS Jan. 12, 1943. w. M. BLAGDEN ETAL 9 3 TRANSMiSSION MECHANISM FOR MOT'OR NEHICLES Filed May 9, 1941 5 Sheets-Sheet 3 Fig.4.

IivEMoRs lwIL IAm MARTIN BLAGDEN l-[ERBERT PERKINS ATTORNEYS 9 4 w. M. BLAGDEN EI'AL 2,303,351

TRANSMISSION MECHANISM FOR MOTOR VEHICLES Filed May 9, 1941 5 Sheets-Sheet 4 5 6 5 J J 7 I v J 5 Q '7" S a I b I ii r i 1 B i\ 9 .47 0/ 2 17 18 3 7a, I

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m a 194 J 19 g- 2 \\l I I INVENTO-RS WILLIAM 141mm: BLAGDEN HERB RT-PE KINS, .9 Bar 2 ATTORNEYS Jam 12,, 19430 Fil ed May 9, 1941 s Sheets-Sheet 5 William Martin Blagden v Herbert, Fuz'kins Patented Jan. 12, 1943 UNITED STATES PATENT OFFICE TRANSMISSION MECHANISM FOR MOTOR VEHICL Application May.9, 1941, Serial'No. 392,760 In Great Britain May 13, 1940- '5 Claims.

This invention relates to transmission mechanism for motor vehicles of the kind described and claimed in United States Patent No.2,2l9',249 having a conventional change speedand reverse gear box, the output shaft of which is coupled direct to the drive shaft of a combined differential, reverse and transfer mechanism disposed centrally between the side members of the vehicle chassis, the drive shaft being disposed longitudinally of the vehicle and carrying forward and reverse pinions or dog clutches which can be selectively coupled to drive differential gear shafts parallel with the drive shaft and'connected by gearing transversely disposed in relation to the vehicle, to longitudinal propeller shafts arranged at opposite sides of the vehicle andito which the wheel drives are connectedgthe .arrangement being such as to enable the .front and rear wheels to be driven in either direction.

In the aforesaid system the central differential splits the drive between the off-side vand near-side of the vehicle while the off-side front and rear wheels are positively coupled by a drive which is geared to one side of the central differential. are also positively coupled by a drive which is geared to the other side of the central differential. V

In transmission mechanism such as previously described the direct coupling of the drive of the front and rear wheels of the vehicle entails'slip between the said wheels and the ground under conditions where the steering of thefront wheels without steering the rear wheels, or vice versa, causes the one wheel to travel in the path of a circle of larger radius than the other wheel. This condition of slip imposes a drag load on the wheels when operating on hard roads which may react on the steering of the vehicle and result in difliculty in operating the steering mechanism, and also increases the rate of tyre wear.

The object of the invention is to provide means for use under certain conditions which are adapted to permit the front wheels to run at speeds different from the rear wheels, thus facilitating the steering of the vehicle, reducing the rate of tyre wear when running on hard roads, and adapted to provide equal torque to the four wheels.

The present invention consists in the provision is incorporated in the drive or output shaftbe-- The near-side front and rear wheels tween the off-side front andrear wheels,'whi1e the other is incorporated in the drive or output shaft between the near-side front and rear wheels.

' The invention further consists in means under manual control of the driver whereby the aforesaid specially adapted differentials may be locked out of action and subsequently unlocked when so desired.

In order that the invention may be clearly understood certain embodiments thereofiwill' now be described by way of example withreference to the accompanying drawings, in which:

Figure l is a skeleton-plan view of a fourwheeled vehicle embodying a transmission mechanism in accordance with the invention.

Figure 2 is a side elevation, on an enlarged scale, of the central part of Figure 1.

I Figures 3 and 4 show respectively a front ;elevation and a sectional plan view, on an enlarged scale, of the transmission mechanism as shown diagrammatically in Figure 1.

, Figure 4A is a sectional plan view complemental to Fig. 4.

, Figure 5 is a longitudinal section, on an enlarged scale, of the spring loaded link mechanism.

;; Figure 6 is a central vertical longitudinal section of the transmisison mechanism.

Figure 7 is a detail vertical section, .on an enlarged scale, taken on the line 1-1 in Fig. 1.

Figure 8 is a section taken on the line 8-8 in Fig. 7.

; According to one convenient mode of carrying the invention into effect in its application to power transmission mechanism of the kind hereinbefore referred to wherein the transmission mechanism comprises a combined diiferentialreverse and transfer gearing which is formed'into a single unit I adapted to be mounted between the longitudinal side members 2 of the frame of the vehicle, and wherein the differential gear shafts 3 have mounted on the ends thereof gear or chain wheels 4 coupled by intermediate gear wheels 5 or chains to gear or chain wheels "6 on output shafts I mounted in transverse extensions 8 formed or fitted to the main casing, said output shafts 1 being disposed longitudinally in relation to the frame of the vehicle and provided at each end with a coupling 9 for attachment to propeller shafts Ill arranged to drive the front and.

rear wheels H and [2, we incorporate with the output shafts I on the near-side and-the oif-side of the vehicle, outer differentials I3 adapted to split the drive between the front and rear wheels I I and I2 respectively and permit the near-side and off-side front wheels I I of the vehicle to run at speeds different from the off-side and nearside rear wheels I2 respectively when the vehicle is steered. The said outer differentials I3 are also adapted to divide the driving torque equally between the four wheels of the vehicle.

As shown in Fig. 6, the central differential gear shafts 3 are driven in forward and reverse direc- 40 to pinion 3! by engaging a dog clutch 42 for forward drive, or may disengage such clutch and engage pinion 38 with gear 39 for reverse drive. The drive shaft 40 is coupled direct to the output shaft of the main gear box 43 by a coupling 44.

The casings I4 of the aforesaid outer differentials I3 have mounted on one end thereof the gear or chain wheels 6 coupled by the intermediate gear wheels 5 or chains to gear or chain wheels 4 on the ends of the central differential gear shafts 3.

' The aforesaid outer differentials I3 are adapted to be locked by manual operation of a lever I5 by the driver of the vehicle, when driving conditions are such that one or more wheels lose grip of the ground and tend to spin, and such is effected by the provision of a sliding clutch I6 mounted on the driven part Ia of the output shafts I, said clutch having formed therein teeth or dogs I! adapted to engage with teeth or dogs I8 formed on the casing I4 of the outer differential, said clutch, when moved to its engaged or operative position, being adapted to lock together the two parts 1, Ia of said output shafts and make inoperative the outer differentials I3 incorporated therewith. In Figures 4 and 4A, the aforesaid sliding clutches I6 are shown in the disengaged or free position. I

The means for operating the aforesaid sliding dog clutches IS in one convenient arrangement comprises forks I9 which may conveniently be carried on shafts 32 mounted in the casing of the outer differentials, as shown in Figs. '7 and 8, said forks being operated by levers 33 fixed, to short vertically disposed shafts I9a mounted in the diiferential casing, the said shafts I90. having mounted on their outer ends levers which are connected, as shown in Fig. 1, by means of spring loaded links 2| to short arms 22 fixed to a cross shaft 23 mounted transversely between the side members 2 of the chassis frame, the said cross shaft 23 having keyed thereon the operating lever I5 arranged and adapted for manual operation by the driver. In order to obtain the appropriate simultaneous movement of the sliding clutches I6, the lever 20 on one side of the vehicle is connected directly to the spring loaded link 2|, while on the other side the connection is through intermediate lever and link mechanism 24.

The aforesaid spring loaded links 2I, as seen in Figure 5, comprise a rod 25 fixed in one end of a tubular member, and a rod 25 slidably mounted in the other end of said tubular member and having fixed on its inner end an abutment 21 on the opposite sides of which react springs 28 and 23. the outer ends of said springs reacting respectively on abutments 30 and 3| mounted in the outer ends of the aforesaid tubular member.

The aforesaid links 2| are adapted to be spring loaded in both directions in order that the manual lever I5 may be operated by the driver under all circumstances, that is assuming the teeth I I on the sliding clutch member I 6 are not in suitable relative positions to slide into engagement with the clutch teeth or dogs I8 on the casings I4 of the outer differentials I3 when said manual lever I5 is operated, movement being taken up in deflecting the springs of the aforesaid spring loaded links 2I, and this deflection causes a spring load to be imposed on the sliding dogs, which will cause said dogs to slide into engagement when suitable relative positions have been attained for meshing. Alternatively, if the sliding dogs are already engaged, the opposite movement of the manual lever I5 will impose spring loads on the sliding dogs I1 and will cause them to disengage as soon as any load imposed by the drive is sufficiently reduced.

It will be readily appreciated that if the driving conditions are such that one or more wheels lose grip of the ground and tend to spin, the outer differentials I3 are thus adapted to be locked and made inoperative at will by manual operation of the aforesaid lever I5 by the driver of the vehicle.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is:

1. In a motor vehicle having a main frame having longitudinal side members, front and rear wheels, a main change speed gear box, parallel propeller shafts disposed longitudinally at opposite sides of the vehicle and connected to the front and rear wheels at the respective sides of the vehicle for driving them, a combined differential, reverse and transfer gearing mounted centrally between the longitudinal side members of the frame and comprising a driving shaft disposed longitudinally of the vehicle and coupled direct to the output shaft of the main gear box, forward and reverse pinions mounted on said driving shaft, differential gearing including differential gear shafts disposed paralle1 to said driving shaft, means for selectively coupling said pinions to said differential gear shafts, gearing disposed transversely of the vehicle and connecting said differential gear shafts to the respective longitudinal propeller shafts for driving them, outer differential gearing incorporated with the propeller or output shafts in the drive between the front and rear wheels of the vehicle, and means under manual control for causing said outer diiferential gearing to act non-difierentially.

2. A motor vehicle according to claim 1, wherein said differential gearing incorporated with the propeller or output shafts comprises two outer differential gears arranged to split the drive between the off-side front and rear wheels and the near-side front and rear wheels, and wherein said means under manual control comprises means for locking and unlocking said gearing.

3. A motor vehicle according to claim 1, wherein said propeller shafts are divided, and said outer differential gearing for each propeller shaft comprises a casing freely mounted on one part of the respective propeller shaft and having a gear wheel thereon connected by intermediate gears to said combined differential, re-

verse and transfer gearing, and wherein said means under manual control comprises a slidable clutch member provided with clutch teeth engageable with clutch teeth on the casing of the respective outer differential gearing for clutching the casing of said outer differential gearing to the other part of the respective propeller shaft.

4. A motor vehicle according to claim 1, wherein said propeller shafts are divided, and said outer differential gearing for each propeller shaft comprises a casing freely mounted on one part of the respective propeller shaft and having a gear wheel thereon connected by intermediate gears to said combined differential, reverse and transfer gearing, and wherein said means under manual control comprises a slidable clutch member provided with clutch teeth engageable with clutch teeth on the casing of the respective outer differential gearing for clutching the casing of said outer differential gearing to the other part of the respective propeller shaft, and lever and link mechanism for actuating said slidable clutch members.

5. A motor vehicle according to claim 1, wherein said propeller shafts are divided, and said outer differential gearing for each propeller shaft comprises a casing freely mounted on one part of the respective propeller shaft and having WILLIAM MARTIN BLAGDEN. HERBERT PERKINS. 

